How good are the screening tests for Down's?

The two main screening tests for Down's Syndrome are a blood test (known variously as the triple test, double test, serum biochemistry or Bart's Test) usually done at 14-18 weeks. This test uses your blood, not the baby's, and picks up about 70% of Down's babies. The other test is the nuchal (neck skin thickness) scan, done at 11-14 weeks. This picks up about 80% of Down''s babies. These tests assume that roughly 5% of women (those with the highest risk results) will end up having an invasive test to know for certain whether the baby has Down's or not. It is now almost certain that a blood test combined with the nuchal scan is best for detecting Down's, with about 90% detection.
How likely is it that my baby will have Down''s syndrome?

The risk of having a baby with Down''s syndrome is related to your age, although parents of any age can have a Down''s child. It is not related to how many children you have had, whether you have a new partner, or to drugs that you might have taken at or around the time of conception.

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What does a nuchal scan show?

"Nuchal" means neck; nuchal ultrasound is carried out at 11 to 14 weeks to look at thickness of a certain area at the back of the fetus'' neck. A particularly thick nuchal pad has been linked with a higher risk of suffering from heart defects, Down syndrome, or some other chromosomal problem. A nuchal scan may follow or be followed by an AFP3, or Triple test, to gain more insight into possible problems. Subsequent amniocentesis, or another invasive diagnostic procedure will help confirm or rule out these problems. Ask your doctor for a complete explanation of all procedures.

What the scan shows The picture shows a normal fetus. The dotted lines indicate where the nuchal pad would be thicker, as in Down syndrome.

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